The present invention relates to cardiac imaging, and more particularly, to estimating 3D cardiac motion from a single scan of C-arm angiography.
Heart disease affects a large number of people globally and has become the leading cause of death in the United States. The estimation of cardiac motion and deformation is an area of concern in medical image analysis, as such cardiac motion and deformation has important clinical implications for the viability of the heart muscle. Various studies have attempted to address estimating cardiac motion and deformation in different imaging modalities, including cardiac computed tomography (CT), ultrasound, and magnetic resonance imaging (MRI).
The recent development of the C-arm image acquisition system provides greater flexibility by enabling generation of real-time fluoroscopy and 3D images of the heart on the same system during an interventional procedure. The C-arm image acquisition system generates a 3D image by reconstructing a 3D image from 2D projections. However, due to cardiac motion, the reconstructed 3D image is typically blurred due to averaging from all projections belonging to different cardiac phases. One possible way to extract cardiac motion is to map every projection to a specific cardiac phase by some registration operation. However, the accuracy of the image after transformation remains a question. Another possible approach is to perform multiple sweeps of the C-arm system and reconstructing a series of 3D images by retrospectively selecting projections that are close to a desired cardiac phase. Each sweep of the C-arm takes about five seconds, and typically six sweeps are necessary to generate enough projections at the same cardiac phase, resulting in a total scanning time of about 30 seconds. In real clinical practice, it is difficult to ask a patient to hold his or her breath for such a long period, especially for a severely ill patient or a patient under general anesthesia. In addition, multiple sweeps consume more contrast agent, which often causes side effects (e.g., allergy or renal insufficiency), and expose patients to more radiation. If only a single sweep is applied, there are a limited number of projection images available for each cardiac phase, which results in reconstruction artifacts due to missing data or residual motion.